1. Field of the Invention
The present invention relates to a joy stick. More particularly, the invention relates to a joy stick in which two swing arms intersecting at right angles are supported by a shaft to transmit the rotational displacement produced by the swinging operation of a lever, and in which a contact switching means is disposed for executing the switching operation upon depressing the lever.
2. Prior Art
A conventional joy stick of this kind will be described with refernce to FIG. 4 In FIG. 4, refernce numeral 1 denotes a joy stick. The joy stick 1 has a box-like casing 2 in wihch two arms 3 and 4 intersecting at right angles up and down are swigable suported by a shaft, and lever 5 passes through the arms 3 and 4 to swing and to slide in the axial direction. Further, a swing plate 6 of nearly a disk-like shape is secured to the lower end of the lever 5, and a protruded surface 6a is formed in nearly a semispherical shape to protrude beyond the lower surface at the center of the swing plate 6.
A guide member 7 is provided under the swing plate 6 to guide the swing plate 6 in the up-and-down direction, and a spring 8 is arranged under the guide member 7 to urge the guide member 7 upward. Under the spring 8 is provided a flexible member 9 of nearly a disk-like shape being made of a flexible material, and a protruded portion 9a is formed at the center of the flexible member 9 to protrude up and down. The upper end of the protruded portion 9a penetrates through the center of the guide member 7 and extends near to the lower end of the swing plate 6. Under the protruded portion 9a is provided a moving contact member made of a flexible material in a dome shape. Under the moving contact member 10 are provided a fixed contact member 11 of an xcexa9-shape as viewed on a plane which is in contact with the moving contact member 10 at all times, and a fixed contact member 12 of a circular shape as viewed on a plane which is separated away form the moving contact member 10.
A bottom plate 13 of the casing of the joy stick 1 is disposed under the fixed contact members 11 and 12, a recessed portion 13a is formed in the upper part of the bottom plate 13 of the casing, the recessed portion 13a having a diameter larger than the moving contact member 10, and the moving contact member 10 and the fixed contact members 11, 12 are secured to the bottom plate 13 of the casing in which the recessed portion 13a is formed.
When the lever 5 is depressed in the direction of an arrow A, the swing plate 6 secured to the lower end of the lever 5 pushes down the protruded portion 9a formed on the flexible member 9. As the flexible member 9 deflects, the protruded portion 9a depresses the moving contact member 10, whereby the moving contact member 10 comes in contact with the fixed contact member 12, so that the circuit between the moving contact member 10 and the fixed contact member 12 is closed.
When the lever 5 is no longer depressed in the direction of the arrow A, the lever 5 automatically returns upward due to the restoring forces of the moving contact member 10, flexible member 9 and spring 8, and the circuit between the moving contact member 10 and the fixed contact member is opened.
When the lever 5 is moved in, for example, the direction of an arrow B, the arm 3 swings, and the displacement in the rotational angle caused by the swing is transmitted to a rotary encoder 14 coupled to an end of the arm 3. In FIG. 4, reference numeral 14A denotes the rotary encoder coupled to the arm 4.
In the above-mentioned conventional joy stick, the swing plate is secured to the lower end of the lever, the guide member is provided under the swing plate to guide the swing plate in the up-and-down direction, and the bottom plate of the casing is disposed under the casing of the joy stick. Therefore, an increased number of parts are required, and the constitution is complex.
Thus, there arouses a technical problem that must be solved for decreasing the number of parts of the joy stick as much as possible, for simplifying the structure and for decreasing the cost. The object of the present invention is to solve this problem.
The present invention was proposed in order to achieve the above-mentioned object, and provides a joy stick in which two swing arms intersecting at right angles are supported by a shaft so as to be operated by the swinging operation of a lever and to transmit the rotational displacement to rotary encoders, and a contact switching means that is switched by the depressing operation of the lever is provided in a casing, wherein an upper end of a spring is brought into contact with the outer circumference of the lever to maintain the attitude of the lever, a support member is provided for limiting the upward displacement of the lever, plural protrusions are formed near the lower end along the outer circumference of the lever to protrude outward and to support the lower end of the spring, the contact switching means is provided on a base plate, and the base plate is used as the bottom plate of the casing.